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Author Topic:   Montauk Transom Repair
RWM posted 04-25-2001 11:15 AM ET (US)   Profile for RWM   Send Email to RWM  
Thanks so much for all your comments and advice on fixing the disaster that occured when my dealer incorrectly mounted my new engine. I've started this new thread in this forum since "Repairs" now more accurately describes where I'm at. Below is the excellent advice from Larry S. that I've copied here, then a couple more questions from me...

From Larry...Bob, Just my opinion, but this is how I would want it repaired.
Drill out unwanted holes oversized enough to get rid of all incorrect material they put in. Then, appropriate sized hardwood dowels should be glued in with an industrial grade (i.e. West System) two part epoxy ("hardware store" five minute epoxy is typically not completely waterproof). Since they are working on a vertical surface, thickening with an appropriate material, such as "Cabosil" (diatomaceous silica) is OK. I would further apply the epoxy until it is flush with the surface and let it set up completely. Then I would countersink the filled area with a Forstner bit (makes a flat bottom hole) a little larger than the hole diameter, to the depth of the thickness of the surrounding gel coat (use a pre-drilled scrap wood guide block to hold the bit in place so as to avoid "walking"). Then, fill the resulting depression with Spectrum factory matched gel coat repair material following the mfrs. instructions, followed by careful wet sanding & polishing. The result will be a high quality, lifetime repair that will hardly be noticeable to the eye.
Having said this, based upon past performance, I would not trust these guys to do it right on their own. Their bad workmanship may be hidden by the finish coat, only to cause problems later. Unfortunately, as long as they are willing to try, you don't have the option of going to someone else and getting Eagle to pay for it. I would therefore demand that the repair be done exactly as you specify (write down the whole process in detail, pay a qualified fiberglass repair shop/surveyor to review/witness the document), and that you are to be present at all times when your boat is worked on. Get this all agreed to in writing. If they refuse, get your boat fixed somewhere else (the ultimate goal) and sue them in small claims court. Good luck, Larry S.

Larry et al...The dealer says he plans to fill the holes with a fiberglass/epoxy/filler mix. Obviously I don't want that and also, as you suggest, I really don't want him working on the boat anymore. That said, I am confident that I can do the repair as you suggest and may just do it myself. I already have all the West System materials since I was going to do some other work on the hull with it and adding the transom doesn't seem like to big a deal as you describe it. I hate to let the dealer off the hook, but maybe doing it myself will be the easiest and best way. Still wresting with it (but feeling better thanks to all the help from this board)...Bob M.

lhg posted 04-25-2001 02:12 PM ET (US)     Profile for lhg    
In that case, just have the Dealer un-install the engine and store it for you while you fix things up. He can give you the bolt hole template that comes with the engine, and you can re-drill the correct holes, and just have him bolt the engine back on. BE SURE your new bolt hole pattern is the INDUSTRY STANDARD pattern. I would assume Suzuki/OMC complies.

When you re-install, raise the engine up 1 bolt hole (3/4") from the "all the way down" position. This should give you the correct performance for an engine in the 70HP range.

RWM posted 04-25-2001 02:29 PM ET (US)     Profile for RWM  Send Email to RWM     
The engine removed was a 1978 Mercury 90. The 2000 Evinrude 70 HP has a completely different bolt pattern. I have no idea if it is "industry standard". FYI if the dealer had mounted the engine "1 bolt hole up" as I had asked him to, he could have bolted the bottom holes with through bolts instead of the lags...Bob
lhg posted 04-25-2001 03:52 PM ET (US)     Profile for lhg    
Here are the industry standard bolt hole dimensions, for 1/2" bolts. I know these were in use at least by 1984, for engines 40hp and up.

Top set of holes: C/L spacing of 12 7/8"
Bottom set of holes: C/L spacing of 9 7/8"

The holes are separated vertically by
C/L spacing of 8".

lhg posted 04-25-2001 03:58 PM ET (US)     Profile for lhg    
RWM - if you want a clear picture of what the standard bolt hole pattern should look like on the inside of your Montauk transom, see the Engine Brackets article in the Reference Section, 3rd picture.
Anchor7 posted 04-27-2001 04:29 PM ET (US)     Profile for Anchor7  Send Email to Anchor7     
RWM - Coincidentally, I had the same engine (1999/2000 Evinrude 70 hp 4-stroke made by Suzuki) on a boat I just recently sold due to non-boating reasons. The engine was great. That engine comes with an installation manual, very detailed, which is different than the owners manual. Usually, dealers never show or give this other manual to customers, too bad. Since a copy of this install manual comes with each new engine, the dealer doesn't need to keep it, and you paid for it. I would get it from him now. Even though you still should use the OMC drill template to make the holes, the install manual has a dimensional drawing of the recommended hole pattern, so you can figure out where they will go in advance.
Tom W Clark posted 04-27-2001 04:53 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I really like Larry S.'s advice for repairing the holes. But I do have one point of dissention, and this applies to other bits of advice I've seen on this site regarding plugging holes.

I do not recommend using a section of dowel, hardwood or otherwise, to plug a hole in your transom, or gunnel board or whatever. The grain of the dowel will be running perpendicular to the grain of the wood. Why is this bad? Wood expands and contracts along its grain at a different rate than across its grain. If you use a hardwood dowel in your transom repair what might happen is that when the motor is bolted on it will crush the transom, and the plywood inside of it, a little bit. The dowel will not compress much and the gelcoat patch will suddenly stand out if not fall out altogether.

In the home building and wood working industry I see this mistake being made all the time. If you have a screw hole in, say, your teak gunnel board you don't glue a chunck of dowel into the hole, you make a plug from a scrap of teak and glue it in cafefully aligning the grain of the plug (or bung) the the grain of the board it is going into. Not only does this look better, but the wood moves in unison and will stay tight and flat longer.

In the case of a Whaler transom I would use plugs made from marine grade plywood or at least from a chunk of mahogany. On a Montauk I suspect the transom has two layers of 3/4" plywood. (does anybody know for sure) Since the transom reinforcement is plywood it won't matter whether the grain is going up or down, just be sure it's not going in and out.

lhg posted 04-27-2001 06:27 PM ET (US)     Profile for lhg    
On all of the BW Wood Locating Diagrams, including those in the Reference section, they say the plywood is "full thickness of transom". With glass and gelcoat on each side of about 1/4", just measure your transom thickness, subtract about 1/2" and the rest is plywood.

Tom W, I would like to say that for a "young" guy of 38, you really know your stuff on Whalers! Thanks for all of your very informative posts, and get yourself another Whaler. I was amazed to see you didn't currently own one. What size will be next?

Dr T posted 09-27-2001 04:10 PM ET (US)     Profile for Dr T  Send Email to Dr T     
I am considering a CMC PT35 power tilt and trim for my old 35 HP on the 13. When I make the switch, I will need to fill the old holes. In light of the advice that Larry Sherman and Tom Clark have given on this, it looks like I will need to drill the current holes out from 5/16 to 3/8 and fill.

Now for the question, will I be able to substitute plugs made of good exterior grade plywood or Starboard for the marine grade plywood Tom suggests? Marine grade plywood of any sort is difficult to find up here in the Rockies, and I understand that exterior grade plywood uses the same glue. The Starboard would have the advantage of being insensitive to moisture (plus I have some on hand).




Now my question:

LarrySherman posted 09-27-2001 04:16 PM ET (US)     Profile for LarrySherman  Send Email to LarrySherman     
I think exterior grade would be fine. Just make sure you fill any voids in the plugs first.


Tom W Clark posted 09-27-2001 08:55 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

When I suggested using plywood for plugs I was thinking of holes larger than 3/8". To answer your question, exterior grade plywood will be just as good as marine grade. You are correct about the glue used in the production of plywood. Marine grade has superior veneers generally, with fewer voids. (In reality, there has been some marine grade plywood in recent years that really wasn't any better than ACX, but this is another story)

I don't think you are going to have success cutting 3/8" plugs from plywood; the plugs will probably fall apart. Just use some wood like Douglas fir if it is not too hard, or mahogany. Or you can do as lhg suggests and just go buy some mahogany plugs, but if you own a plug cutter then just grab a scrap of 2x4 and plug away.

When it comes time to glue them into your transom, just keep feeding the plugs in until the thickness of the transom is filled.

I wouldn't use Starboard because this is not what is in your transom.

Larry, thanks for the kind words: I don't know what my next Whaler will be. 20', 22', or 25'? I'd really like to come up with an old 13' project boat for my nephews. Got any suggestions?

grandmufti posted 09-27-2001 09:11 PM ET (US)     Profile for grandmufti  Send Email to grandmufti     
While on the subject of transoms.What is the proper way to seal the mounting bolt holes for the motor?
acseatsri posted 09-27-2001 09:23 PM ET (US)     Profile for acseatsri  Send Email to acseatsri     
3M 5200 - What else is there?
lhg posted 09-27-2001 09:30 PM ET (US)     Profile for lhg    
How about Boatlife (or similar) polysulfide silicon sealant, for below waterline use? Respectfully disagree with the 5200 recommendation.
Tom W Clark posted 09-27-2001 09:33 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
For sealing the mounting bolt holes, many dealers use silicone. Works fine. The 3/8" bolts are big enough that 3M 5200 will begin to pose a problem when it comes time to remove them but it will work as will 3M 4200, Sika 1A, Sika 231, Sika 240, Sika 241, 3M 101 (polysulphide).

I would use cheap silicone as it will be fairly easy to rub off the transom when it comes time to remove the motor. Of the polyurethanes above, Sika 231 would be best as it is intended as more of a bedding sealant and does not have the adhesive power of the others. The polysulphides will work nicely too.

dfmcintyre posted 09-27-2001 09:53 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
According to the fiberglass repair shop that worked on my whaler, most installs end up with water penetration due to the bedding compound degrading. And it's tough to tell when it goes.

What they do, after installing a NEW transom, is a two day project, which is why most dealers don't do it this way. They oversize the mounting holes, tape over one hole and pour resin in and let it setup overnight. Next day, redrill the proper size. This way, if there is water penetration, the wood is protected, by a resin "pipe".

There are references to this type of procedure (for mounting into a resin "plug") in the West System lit. and in an earlier post that pointed to another URL. The boating industry is still having problems with cored hulls and cabin tops, especially with after factory installed items.


grandmufti posted 09-27-2001 09:56 PM ET (US)     Profile for grandmufti  Send Email to grandmufti     
Thanks for the replies.Guess I have to make a decision based on the sealant properties.What bothers me,is no matter how hard I try I am never sure if it is truly sealed as most of the sealant comes out of the hole when i put the bolt in.I never know if there is sealant between the hull and transom.
willyjoe1 posted 09-28-2001 12:37 AM ET (US)     Profile for willyjoe1  Send Email to willyjoe1     
drT, why are you not drill new holes at cmc tnt bracket, instead putin more holes at the transom,i think this cmc pt35 ptnt with 5 1/2" setback [24 lbs] will be too much weight for your 13,
Dr T posted 09-28-2001 01:36 AM ET (US)     Profile for Dr T  Send Email to Dr T     
Tom, thanks again for the advice. I may go looking for some pre-made mahogony plugs. If the holes are clean, I may use 5/16 if I can find them. If I bore them out, then it will be the 3/8.


The new holes are to mount the CMC bracket to the transom (It will not use the same holes as the old 1982 motor, which uses two bolts and two clamps). The 35 will mount to the CMC which will provide a 5.5 in setback and 3 in rise. Since the old 35 is a very light engine, the combined weight is less than a new 40 hp with PTT. Given the experience of some others on the site, I am not particularly worried about the ability. of the transom to handle the load. Thanks for asking.

jimh posted 09-28-2001 02:23 PM ET (US)     Profile for jimh  Send Email to jimh     
Anything that leads water into cored material can be a headache.

A co-worker finally found a buyer for his boat this summer. On survey one of the running lights was out. Inspection of the lamp housing showed the mounting screws had not been well sealed and water, which had been collecting in the poorly designed and poorly sealed running light housing, had been getting into the cored deck.

A large section of the cored deck was rotted and the estimate on repairs was several thousand dollars. The buyer negotiated a suitable price reduction.

It just goes to show that something as simple as a #8 sheet metal screw being poorly sealed can result in thousands of dollars of damage over just a few seasons.

Incidently, the seller recalled that he had to replace the bulb in that running light on several occassions. He never realized that the water that was getting in (on the top) was going out the bottom and into his deck.


seacast posted 10-24-2002 11:04 AM ET (US)     Profile for seacast  Send Email to seacast     
For future transom repairs, check out Seacast is a composite that replaces wood in your boat transom and stringers, will not rot and is triple the strength of marine plywood.

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